After studying theater at Orange Coast College, in Costa Mesa, California, Forstadt began her acting career by working at Knott's Berry Farm's Bird Cage Theater, performing melodramas, often as the damsel in distress character. Later, she went to Hollywood where she worked as a wardrobe mistress on such television shows as The White Shadow and Hill Street Blues, as well as for the film S.O.B.. She also spent several years doing live theater in the Los Angeles area. Most notably, she won some recognition for her portrayal of the character Josette in the world premiere of Eugène Ionesco's Tales for People Under 3 Years of Age at the Stages Theatre Center in 1982. She starred in several low-budget movies such as Mugsy's Girls, with Ruth Gordon and Laura Branigan, and Round Numbers with Kate Mulgrew, Samantha Eggar, and Shani Wallis. She also appeared as a television actress in Hill Street Blues, St. Elsewhere, and L.A. Law. Her voice acting breakthrough came when she landed the leading role of Lynn Minmei in the English version of Robotech, the popular anime series of the 1980s. Since then, she has voiced hundreds of other anime characters and has branched into non-anime cartoons, live-action shows (such as Masked Rider and Power Rangers: Time Force), commercials and radio work, and has performed background voices for movies such as Antz, Dr. Dolittle, and The Santa Clause.

Rebecca is a personal friend of mine. Met her at a Robotech convention in the 80's when I was a boy, and I've stayed in touch with her ever since. She can do so many variations of her voice, it's really cool.